Vascular filter with improved anchor or other position retention

Abstract

The present invention relates to a vascular filter which can be placed in a blood vessel, for the purpose of intercepting thrombus, and which has improved structural features for enhancing position stability at the desired site. These features may include improved barbs or anchor designs. An example of an improved anchor for retaining a vascular filter in position includes for example cutting a barb member from a circumferential side of a filter member or rib, or bending part of a barb slightly in an outward direction to form a gentle spring, or a bevel or bend of an outwardly extending barb toward the longitudinal direction. The various features of the present invention may be used singly or in any combination, as desired in a particular vascular filter.

What is claimed is:  
     
         1 . A vascular filter for placement inside a blood vessel to treat a patient, comprising: 
 in a radially compressed state, a tubular metal cylinder having a first and second integral cylindrical end collar at a proximal and distal end of the vascular filter; a plurality of ribs arranged in a preselected pattern and extending between the first and second end collar in a direction essentially parallel to a longitudinal axis of the vascular filter;    in a radially expanded deployed state, the ribs tend to resiliently expand outward in radial directions, thereby causing the first and second end collars to move toward each other; each of the ribs tending to spread apart, such that the vascular filter defines a plurality of central polygon shapes arranged adjacently around a central circumference of the vascular filter, each polygon shape being defined by structural members including at least one rib extending essentially parallel to the longitudinal axis of the vascular filter; the vascular filter further defining a first and second end filter portion connecting the central polygons with the end collars, wherein the end filter portions each define a plurality of diamond filter cells; each of the filter cells being formed by a plurality of members; the filter cells all extending along a first and second end cone;    at least one anchor extending outward in a radial direction from at least one of the ribs in the expanded deployed state, which tends to resist longitudinal movement of the filter in a blood vessel, the anchor being defined by one longitudinal cut in a rib essentially parallel to the longitudinal axis, and at least one angled cut in the rib extending from the longitudinal cut to a side of the rib;    such that upon compression and removal of the filter from a blood vessel, the anchor tends to retract radially inward and facilitate removal.    
     
     
         2 . The vascular filter as set forth in  claim 1 , wherein an angle defined by the angled cut and the longitudinal cut is an acute angle.  
     
     
         3 . The vascular filter as set forth in  claim 1 , wherein an angle defined by the angled cut and the longitudinal cut is an obtuse angle.  
     
     
         4 . The vascular filter as set forth in  claim 1 , wherein a tip portion of the anchor is bent in a radially outward direction, such that a remainder of the anchor tends to act as a spring and gently urge the tip portion of the anchor to engage the blood vessel.  
     
     
         5 . The vascular filter as set forth in  claim 4 , wherein a main portion of the anchor is bent in a radially inward direction, and a tip portion of the anchor is bent essentially parallel to the longitudinal axis of the stent.  
     
     
         6 . The vascular filter as set forth in  claim 1 , characterized in that the construction of the filter is such that it has been formed out of one single unitary metal element.  
     
     
         7 . The vascular filter as set forth in  claim 1 , adapted for use in the vena cava.  
     
     
         8 . The vascular filter as set forth in  claim 1 , wherein the polygon shapes are hexagons.  
     
     
         9 . The vascular filter as set forth in  claim 4 , wherein the filter cells have a diamond shape with four sides, defined by a first and second rib each forming a portion of a first and second of the hexagon shapes, and by a first and second conical rib directly connecting an apex of the first and second of the central hexagon shapes with the end collars respectively.